fix build on mac (take II)

Author: jef-n

src/app/qgsoptions.cpp

@@ -738,9 +738,9 @@ void QgsOptions::toggleStandardDeviation( int state )
   }
 }
 
-#ifdef Q_WS_X11
 void QgsOptions::toggleEnableBackbuffer( int state )
 {
+#ifdef Q_WS_X11
   if ( Qt::Checked == state )
   {
     labelUpdateThreshold->setEnabled( false );
@@ -751,8 +751,10 @@ void QgsOptions::toggleEnableBackbuffer( int state )
     labelUpdateThreshold->setEnabled( true );
     spinBoxUpdateThreshold->setEnabled( true );
   }
-}
+#else
+  Q_UNUSED( state );
 #endif
+}
 
 QString QgsOptions::theme()
 {

src/app/qgsoptions.h

@@ -74,11 +74,9 @@ class QgsOptions : public QDialog, private Ui::QgsOptionsBase
 
     void toggleStandardDeviation( int );
 
-#ifdef Q_WS_X11
     //! Slot to change backbuffering. This is handled when the user changes
     // the value of the checkbox
     void toggleEnableBackbuffer( int );
-#endif
 
     /**
      * Return the desired state of newly added layers. If a layer